Agricultural machine

ABSTRACT

An agricultural machine ( 2 ) comprises an operating unit ( 6 ) and a carrier assembly ( 8 ) for the operating unit. The carrier assembly ( 8 ) includes a carrier arm ( 12 ) and a suspension system ( 16 ) by which the operating unit ( 6 ) is suspended from the carrier arm ( 12 ). The suspension system ( 16 ) including two pairs of connecting rods, comprising a pair of upper connecting rods ( 28 ) and a pair of lower connecting rods ( 30 ), each said connecting rod being attached via joints ( 32 ) to the operating unit ( 6 ) and the carrier arm ( 12 ). A first pair ( 30 ) of said upper and lower connecting rods diverge in a working direction of the operating unit and a second pair ( 28 ) and of said upper and lower connecting rods converge in a working direction of the operating unit.

The present invention relates to an agricultural machine and a carrierassembly for an operating unit of an agricultural machine. In anembodiment the invention relates to an agricultural mowing machine and acarrier assembly for a cutter unit of an agricultural mowing machine.

More generally, embodiments of the invention relate to various kinds ofagricultural machine including, but not limited to, mowing machines,rakes, tedders, seeding machines and soil working machines, includingdisc harrows and cultivators. Further embodiments of the inventionrelate to a carrier assembly for an operating unit of an agriculturalmachine, where the operating unit is a cutter unit, a rake, a tedder, aseeding machine or a soil working machine.

A known type of agricultural mowing machine that may be used forharvesting hay, straw and similar crops has a cutter unit comprising aplurality of rotary cutter heads attached to a cutter bar. The cutterheads rotate about vertical axes and are provided with cutter bladesthat cut the crop. The rotary cutter heads may be of the disc-type ordrum-type. The mowing machine may be a conditioning mowing machine thatincludes a plurality of flails for conditioning the cut crop, or a plainmowing machine that has no conditioning unit.

The operating unit may be carried by a carrier vehicle, for example atractor. In the case of an agricultural mowing machine cutter units maybe mounted on one or both sides of a tractor or other agriculturalcarrier vehicle, each cutter unit being carried by a carrier assemblythat includes a carrier arm and is attached to the rear of the tractor.The carrier assembly may include a pivot mechanism that allows theposition of the carrier arm to be adjusted. The carrier arm may forexample be located in a cutting position in which the cutter unit ispositioned close to the ground to cut the crop, or a transport positionin which the cutter unit is lifted behind the cab of the tractor,allowing the tractor to travel along a road. The carrier arm or thecutter unit may also be raised to a headland position in which thecutter unit is lifted a small distance above the cutting position,allowing the tractor to turn when it reaches the headland.

Other types of agricultural machine including rakes, tedders, seedingmachines and soil working machines may be mounted in a similar mannerwith an operating unit (a rake, tedder, seeding machine or soil workingmachine) mounted on one or both sides of a tractor and carried by acarrier assembly that includes a carrier arm and is attached to the rearof the tractor. Again, the carrier assembly may include a pivotmechanism that allows the position of the carrier arm to be adjusted.The carrier arm may be located in an operating position in which theoperating unit is positioned close to the ground or a transport positionin which the operating unit is lifted behind the cab of the tractor,allowing the tractor to travel along a road. The carrier arm or theoperating unit may also be raised to a headland position in which theoperating unit is lifted a small distance above the operating position,allowing the tractor to turn when it reaches the headland.

A mowing machine of the general type described above is disclosed in DE29614199U1. A cutter unit is suspended from the end of a carrier armthrough a pivot joint, which is located centrally between the ends ofthe cutter unit. The pivot joint has a pivot axis that extends parallelto the working direction of the mowing machine and the cutter unit canrotate about this axis during use, allowing it to follow the contours ofthe ground. The carrier arm can be lifted from the cutting position to atravelling position in which the cutter unit is carried behind thetractor.

A disadvantage with the mowing machine described in DE 29614199U1 isthat it does not allow for sideshift (sideways movement of the mowingunit) relative to the axis of the tractor. Sideshift may be usefuleither when setting the machine up, for example to provide differentoperating widths, or to allow lateral adjustment of the sutter unitrelative to the tractor during mowing, for example to ensure a constantoverlap with a previously cut strip. Also, even if sideshift werepossible, DE 29614199U1 does not disclose any mechanism for adjustingthe energy level of any energy accumulators (for example springs orhydraulic bladders) associated with the carrier arm, in order tocompensate for changes in the turning force transmitted through thecarrier arm. Sideshift movement of the mowing unit is thereforeimpractical in the mechanism disclosed in DE 29614199U1.

Also, if the cutter unit strikes an obstacle on the ground during amowing operation this can cause the cutter unit to twist about asubstantially vertical axis, placing a strain on the pivot joint andpossibly leading to damage or failure of the pivot mechanism. Theproblem is particularly acute if the cutter unit strikes an obstaclenear to one of its ends.

Also, it is not possible to adjust the height of the cutter unitrelative to the carrier arm. Therefore, when working on uneven groundany vertical movement of the cutter unit relative to the tractor has tobe accommodated by movement of the carrier arm, which places significantloads on any energy accumulators (for example springs or hydraulicbladders) associated with the arm.

EP 0945051B1 describes another mowing machine in which the cutter unitis suspended from the carrier arm by a swivel joint at the centre of thecutter unit. The swivel joint is configured to allow rotation of thecutter head about a first pivot axis that extends parallel to theworking direction of the mowing machine. The swivel joint also allowsrotation of the cutter head about a second axis that is perpendicular tothe first axis: the second axis may for example be a substantiallyvertical axis. As with the mechanism described in DE29614199U1,sideshift movement of the mowing unit is neither possible nor practicalin the mechanism disclosed in EP 0945051B1.

In EP 0945051B1 the cutter unit can rotate about the first axis duringuse, allowing it to follow the contours of the ground. It can alsorotate to a limited extent about the second axis, reducing the risk ofsubjecting the pivot joint to damaging shocks if the cutter unit strikesan obstruction on the ground.

In order to maintain the mowing machine cutter unit in the correctworking position with the cutter unit perpendicular to the workingdirection, a pair of control rods are provided at the inner end of thecutter unit, which are connected to the cutter unit and to the carrierarm through ball joints. These control rods allow rotation of the cutterhead about the first pivot axis but prevent rotation of the cutter headabout the perpendicular second axis.

The suspension mechanism described in EP 0945051B1 overcomes some of theproblems described above in relation to DE 29614199U1. Specifically,straining of the pivot joint between the cutter unit and the carrier armis reduced or avoided. However, the control rods restrict the range ofmovement of the cutter head about the first pivot axis, which could meanthat the cutter head is unable to follow large contours in the ground.They also prevent lateral adjustment of the position of the cutter unitrelative to the tractor. The mechanism is also rather complex andincreases the weight of the mowing machine. In addition, when thecarrier arm is lifted to the transport position the position of thecutter head is not well controlled. This can cause problems for examplewhen travelling along a road with the mowing machine cutter unit in thetransport position.

Also, in EP 0945051B1 it is not possible to adjust the height of thecutter unit relative to the carrier arm. Therefore, when working onuneven ground any vertical movement of the cutter unit relative to thetractor has to be accommodated by movement of the carrier arm, whichplaces significant loads on any energy accumulators (for examplessprings or hydraulic bladders) associated with the arm.

Similar problems arise with other types of agricultural machine that arecarried by a carrier assembly including a carrier arm attached to therear of a tractor.

It is an object of the present invention to provide an agriculturalmachine and a carrier assembly for an agricultural machine thatmitigates one or more of the aforesaid problems.

According to one aspect of the present invention there is provided anagricultural machine comprising an operating unit and a carrier assemblyfor the operating unit, the carrier assembly including a carrier arm anda suspension system by which the operating unit is suspended from thecarrier arm, said suspension system including two pairs of connectingrods, comprising a pair of upper connecting rods and a pair of lowerconnecting rods, each said connecting rod being attached via joints, forexample ball joints, to the operating unit and the carrier arm, whereina first pair of said upper and lower connecting rods diverge in aworking direction of the operating unit and a second pair of said upperand lower connecting rods converge in a working direction of theoperating unit.

The suspension system allows the operating unit to be suspended solelyfrom its centre point, thus permitting pendular movement of theoperating unit about the pivot point and allowing the operating unit tofollow the contours of the ground. However, the suspension system ismuch stronger and less vulnerable to damage from striking obstacles onthe ground than the simple pivot used in the mowing machine described inDE 29614199U1. At the same time the complexity and weight of the machinedescribed in EP 0945051B1 is avoided.

The single suspension point also allows the position of the operatingunit to be adjusted laterally relative to the tractor, for example byproviding a telescopic carrier arm. By adjusting the lateral positionsof one or more operating units while negotiating a curve, the risk ofleaving untreated areas of ground can be avoided. A system for adjustingthe positions of the cutter units of a mowing machine is described forexample in EP 1321027 B.

The suspension system allows the height of the operating unit relativeto the arm to change and this movement may be accommodated, for exampleby means of a single actuator or spring. Vertical movement of theoperating unit, as caused for example by movement over uneven ground,can therefore be accommodated without adjusting any energy accumulatorsassociated with the carrier arm, regardless of the length of the arm.The suspension system operates independently of any mechanism foradjusting the position or length of the carrier arm, thereby simplifyingoperation of the machine.

The suspension system also allows the height of the operating unitrelative to the arm to be readily adjusted, for example by means of asingle actuator or spring, which can be located centrally on therotation axis so that it does not affect pendular motion of theoperating unit when working.

Furthermore, when the mowing machine is raised to a transport positionthe operating unit naturally adopts a stable position under the force ofgravity. The stability of the operating unit when it is in this positionmay be increased by the provision of an actuator and/or spring thatexerts a self-righting force on the operating unit. This actuator/springis preferably connected to the carrier arm at a point higher than thevirtual axis of rotation of the operating unit when it is in a raisedposition so that it acts to increase the stability of the unit.

Advantageously, the suspension system includes a support mechanismconfigured to support the weight of the operating unit. The supportmechanism may be located at the free end of the carrier arm, allowingthe operating unit to move vertically relative to the arm and reducingor eliminating the need for the arm to pivot during working toaccommodate undulations in the ground. This reduces the load on theenergy accumulators associated with the arm and allows the energy levelof the energy accumulators to be adjusted directly so as to influencethe behaviour of the support mechanism, regardless of the position orlength of the carrier arm.

The support mechanism may include an actuator configured to adjust theheight of the operating unit relative to the carrier arm. This allowsthe height of the operating unit to be adjusted easily, for examplebetween a working position and a headland position, or in the case of amowing machine between different cutting positions providing differentcutting heights. Preferably, the actuator is configured to act betweenthe operating unit and the carrier arm.

The support mechanism may optionally include a resilient support elementor elements configured to support at least part of the weight of theoperating unit. The resilient support element or elements is preferablyconfigured to act between the operating unit and the carrier arm.Alternatively, the resilient support elements may be omitted and theweight of the operating unit may be supported entirely by an actuator,for example hydraulic actuator, which may optionally be coupled to ahydraulic accumulator.

Advantageously, the upper connecting rods lie in an upper plane and thelower connecting rods lie in a lower plane. In a preferred embodiment aline normal to the upper plane and a line normal to the lower plane aresubstantially perpendicular to a width axis of the operating unit.Preferably, the upper plane is substantially parallel to the lowerplane. This arrangement ensures that the operating unit is held uprightand does not rotate about a horizontal axis as it moves in a verticaldirection relative to the carrier arm.

Advantageously, the carrier assembly includes a mounting structureconfigured for mounting the operating unit on a carrier vehicle and apivot mechanism configured to allow pivoting movement of the carrier armrelative to the mounting structure about a pivot axis that extendssubstantially parallel to the working direction of the agriculturalvehicle. This allows the carrier arm to move between a working positionand a transport position in which the operating unit is located behindthe cab of the carrier vehicle. The carrier assembly preferably includesa drive mechanism for driving pivoting movement of the carrier arm,allowing it to be moved easily between the different positions. Thepivot mechanism is preferably configured to provide for pivotingmovement of the carrier arm between an upright position in which the armis substantially vertical and a lowered position in which the armextends substantially parallel to the ground. The upright positionallows the operating unit to be stowed behind the cab of the carriervehicle for transportation along roads or through narrowgateways/doorways. When the arm is in the lowered position the operatingunit may be configured in a working position or a headland position.

The carrier arm preferably includes an inner arm section and an outerarm section that can be extended relative to the inner arm section toadjust the length of the carrier arm, allowing the position of theoperating unit to be adjusted laterally relative to the carrier vehicle.Advantageously, the agricultural machine includes an actuator foradjusting the length of the carrier arm. This makes it possible toadjust the operating position of the cutter unit during a mowingoperation, for example to ensure that the edge of the cut strip of cropis aligned correctly with the edge of a strip cut previously. Adjustmentof the lateral position of the cutter unit may be carried outautomatically or semi-automatically, for example using an operatingmethod as described in EP1321027B1.

In one preferred embodiment the machine is a mowing machine and theoperating unit is a cutter unit. The cutter unit preferably includes aplurality of rotary cutter heads mounted on a cutter bar or supportframe.

According to another aspect of the invention there is provided a carrierassembly for carrying the operating unit of an agricultural machine, thecarrier assembly including a carrier arm and a suspension system bywhich the operating unit can be suspended from the carrier arm, saidsuspension system including a mounting structure for attaching thesuspension system to an operating unit and two pairs of connecting rodscomprising a pair of upper connecting rods and a pair of lowerconnecting rods, each said connecting rod being attached via joints tothe mounting structure and the carrier arm, wherein a first pair of saidupper and lower connecting rods diverge in a working direction of theoperating unit and a second pair of said upper and lower connecting rodsconverge in a working direction of the operating unit. The carrierassembly may be used for retrofitting to an existing conventionaloperating unit to provide the advantages set out herein.

The carrier assembly may also include one or more features of theagricultural machine as set out in the preceding statements ofinvention.

In one preferred embodiment, the agricultural machine is a mowingmachine and the operating unit is a cutter unit.

Certain embodiments of the invention will now be described by way ofexample with reference to the accompanying drawings, in which:

FIG. 1 is an isometric view of a first mowing machine according to anembodiment of the invention mounted on the rear of a tractor, shown in atransport position;

FIG. 2 is an isometric view of the first mowing machine, shown in araised headland position;

FIG. 3 is a simplified isometric view of a suspension system that formspart of the first mowing machine;

FIG. 4 is an isometric view showing schematically certain components ofthe suspension system;

FIG. 5 is an isometric view of the first mowing machine shown in araised headland position;

FIG. 6 is a side view of the first mowing machine shown in the raisedheadline position;

FIG. 7 is an isometric view of the first mowing machine shown in aworking position;

FIG. 8 is a side view of the first mowing machine shown in a workingposition;

FIG. 9 is an isometric view of the first mowing machine shown in alowered position;

FIG. 10 is a side view of the first mowing machine shown in the loweredposition;

FIG. 11 is an isometric view of the first mowing machine with the mowingmachine shown in a working position;

FIG. 12 is an isometric view of the first mowing machine with the mowingmachine unit shown in a raised headland position;

FIG. 13 is an isometric view of the first mowing machine unit with themowing machine unit shown in a lowered position;

FIG. 14 is an isometric view from above of a suspension system thatforms part of the first mowing machine, showing components of thesuspension system in more detail;

FIG. 15 is an isometric view of a second mowing machine according to anembodiment of the invention mounted on the rear of a tractor, shown in atransport position;

FIG. 16 is an isometric view of the second mowing machine, shown in araised headland position;

FIG. 17 is an isometric view showing schematically certain components ofthe suspension system;

FIG. 18 is an isometric view of the second mowing machine shown in araised headland position;

FIG. 19 is a side view of the second mowing machine shown in the raisedheadline position;

FIG. 20 is an isometric view of the second mowing machine shown in aworking position;

FIG. 21 is a side view of the second mowing machine shown in a workingposition;

FIG. 22 is an isometric view of the second mowing machine shown in alowered position;

FIG. 23 is a side view of the second mowing machine shown in the loweredposition;

FIG. 24 is an isometric view of the second mowing machine with themowing machine shown in a working position;

FIG. 25 is an isometric view of the second mowing machine with themowing machine unit shown in a raised headland position;

FIG. 26 is an isometric view of the second mowing machine unit with themowing machine unit shown in a lowered position, and

FIG. 27 is an isometric view from above of a suspension system thatforms part of the second mowing machine, showing components of thesuspension system in more detail.

FIGS. 1 and 2 depict a first mowing machine 2 according to an embodimentof the invention, which is attached to the rear of a tractor 4 through aconventional three-point mounting system. It should be understoodhowever that the invention is also applicable to other kinds ofagricultural machine including rakes, tedders, seeding machines and soilworking machines, in which an operating unit is attached to the rear ofa tractor 4.

The mowing machine 2 includes an operating unit 6 comprising a cutterunit and a carrier assembly 8 for the cutter unit. The carrier assembly8 includes a mounting structure 10 that is attached to the tractor'sthree-point mounting system, a carrier arm 12 that is attached to themounting structure 10 through a pivot mechanism 14, and a suspensionsystem 16 through which the cutter unit 6 is suspended from the free endof the carrier arm 12.

The pivot mechanism 14 allows the carrier arm 12 to be pivoted about apivot axis X that extends substantially parallel to the workingdirection D of the cutter unit 6 and includes an actuator 18, forexample a hydraulic ram, that can be activated to adjust the rotationalposition of the arm 12 about the pivot axis X. In FIG. 1 the mowingmachine is shown in a transport configuration in which the carrier arm12 is lifted to an upright position so that the cutter unit 6 is locatedbehind the cab of the tractor 4, while in FIG. 2 the carrier arm 12 isshown in a lowered position in which the carrier arm 12 and the cutterunit 6 are substantially parallel to the ground. When the carrier arm 12is in the lowered position the cutter unit 6 may be adjusted relative tothe carrier arm between a working position and a headland position(shown in FIG. 2) in which it is raised slightly above the workingposition.

The carrier arm 12 includes an inner section 20, an actuator 21 and anouter section 22 that can be extended telescopically relative to theinner section 20 to adjust the lateral position of the cutter unit 6relative to the tractor 4. The actuator 21 may for example be ahydraulic ram located within the carrier arm 12. The telescopic carrierarm 12 thus allows for sideshift movement of the cutter unit 6 relativeto the tractor 4. This allows the operating position of the cutter unit6 to be adjusted laterally relative to the centreline of the tractor 4.This makes it possible to adjust the operating position of the cutterunit 6 during a mowing operation, for example to ensure that the edge ofthe cut strip of crop is aligned correctly with the edge of a strip cutpreviously. Adjustment of the lateral position of the cutter unit may becarried out automatically or semi-automatically, for example using anoperating method as described in EP1321027B1.

The cutter unit 6 is largely conventional and includes a plurality ofcutter heads 23 attached to a support frame 24 and an optionalconditioning unit 25 for conditioning the crop cut by the cutter heads.The cutter unit 6 is driven via a drive shaft (not shown) from the powertake-off unit of the tractor 4.

The cutter unit 6 is suspended from the free end of the carrier arm 12by the suspension system 16, which is shown most clearly in FIG. 2.Components of the suspension system 16 are also shown schematically inFIGS. 3 and 4, together with the carrier arm 12 and the support frame 24of the cutter unit. The suspension system 16 includes two pairs ofconnecting rods, comprising a pair of upper connecting rods 28 and apair of lower connecting rods 30. The connecting rods 28, 30 all extendapproximately in the working direction of the mowing machine and areattached via ball joints 32 to the cutter unit 6 and the carrier arm 12.

The rear end of each connecting rod 28,30 is attached via a sphericalball joint to a mounting structure 34 that extends upwards from thesupport frame 24 of the cutter unit 6 and is located approximatelycentrally with respect to the working width of the cutter unit. In thisembodiment the mounting structure includes two pairs of tall innerplates 36 that are connected to the upper connecting rods 28 and twopairs of shorter outer plates 38 that are connected to the lowerconnecting rods 30. The ball joints 32 at the rear ends of theconnecting rods 28,30 lie in a first plane as shown in FIG. 4, referredto herein as the mo-unit plane 40. As can be seen in FIG. 4, the balljoints 32 at the rear ends of the upper connecting rods 28 arepositioned more closely together than the ball joints 32 at the rearends of the lower connecting rods 30.

The forward end of each connecting rod 28, 30 is attached via a secondspherical ball joint 32 to a second mounting structure 42 provided atthe free end of the carrier arm 12. In this embodiment the secondmounting structure 42 includes two pairs of upper plates 44 provided onthe upper part of the carrier arm 12 and two pairs of lower plates 46provided on the lower part of the carrier arm 12. Each of the connectingrods 28, 30 is connected to one of these plates via a second ball joint32. The second ball joints lie in a second plane as shown in FIG. 4,referred to herein as the frame plane 48. As can be seen in FIG. 4, theball joints at the forward ends of the lower connecting rods 30 arepositioned more closely together than the ball joints at the forwardends of the upper connecting rods 28.

The upper connecting rods 28 lie in an upper plane and the lowerconnecting rods lie in a lower plane, and in this embodiment the upperplane is parallel to the lower plane. More generally, a line normal tothe upper plane and a line normal to the lower plane are eachsubstantially perpendicular to a width axis of the cutter unit. Thisarrangement allows the cutter unit 6 to move substantially verticallyrelative to the carrier arm 12 while maintaining the cutter unit in anupright position (i.e. without rotation of the cutter unit about ahorizontal axis). Alternatively, the upper and lower planes may benon-parallel, in which case vertical movement of the cutter unitrelative to the carrier arm will cause a degree of rotation of thecutter unit 6 about a horizontal axis, which may be permissible incertain applications.

As explained above, the ends of the upper connecting rods 28 are closertogether in the mo-plane 40 than the frame plane 48, and the upperconnecting rods 28 therefore converge from the frame plane towardsmo-plane. Conversely, the ends of the lower connecting rods 30 arefurther apart in the mo-plane 40 than the frame plane 48 and the lowerconnecting rods 30 therefore diverge from the frame plane to themo-plane. The upper and lower connecting rods 28, 30 therefore act likereversed A-frames, which prevent horizontal movement of the cutter unit16 relative to the carrier arm 12.

Because the connecting rods 28, 30 are connected to the carrier arm 12and the mounting structure 34 of the cutter unit 6 via ball joints, thecutter unit is able to rotate relative to the carrier arm about an axisof rotation R that extends approximately in the working direction of thecutter unit. This allows the cutter unit to follow the contours of theground while working.

As illustrated in FIG. 4, the actual axis of rotation R extends betweentwo points, one in the mo-plane 40 and the other in the frame plane 48,each point being located at the intersection of lines drawn between theattachment points of diagonally opposed ball joints 32. The axis ofrotation R therefore lies in a vertical plane that is parallel to theworking direction D of the cutter unit, but is inclined downwards in theworking direction.

It should be understood that the connecting rod arrangement illustratedin FIGS. 3 and 4 may be inverted, whereby the upper pair of connectingrods 28 diverge from the frame plane 48 to the mo-plane 40 and the lowerpair of arms 30 converge from the frame plane 48 to the mo-plane 40.This does not affect operation of the suspension system 16.

The suspension system 16 also includes an actuator mechanism 50 foradjusting the height of the cutter unit 6 relative to the carrier arm12, which is shown most clearly in FIG. 14. In this example, theactuator mechanism includes a hydraulic ram 52 that extends from a firstpivot point 53 a between the rear ends of the upper connecting rods 28to a second pivot point 53 b between the forward ends of the lowerconnecting rods 30. The actuator mechanism 50 also includes acompression spring 54 and a pair of tension springs 60, which extend oneither side of the hydraulic ram from a first connection point close tothe rear ends of the lower connecting rods 30 to a second connectionpoint close to the forward ends of the upper connecting rods 28. Thesprings 54, 60 act with the hydraulic ram 52 and help to support theweight of the cutter unit. By supplying hydraulic fluid to the ram 52 itcan be extended thereby lifting the cutter unit 6 to the raised positionshown in FIGS. 5, 6 and 12. Reducing the quantity of hydraulic fluidsupplied to the ram 52 allows the cutter unit to fall under gravity tothe working position shown in FIGS. 7, 8 and 11, and subsequently to thelowered position shown in FIGS. 9, 10 and 13, for example for cleaningor maintenance.

The suspension system therefore allows the height of the cutter unit 6relative to the carrier arm 12 to be adjusted and allows the cutter unitto rotate about an axis R that extends substantially in the workingdirection D, but does not allow the cutter unit 6 to move laterallyrelative to the carrier arm (i.e. in a direction that is parallel to thewidth of the cutter unit). The cutter unit 6 can therefore rotate toaccommodate undulations in the surface of the ground. The height of thecutter unit 6 relative to the carrier arm 12 can also be adjusted eitherto adjust the height of cut of the cutter unit, or to allow the cutterunit to be positioned in a raised headland position as shown in FIGS. 5and 6 that allows the tractor to perform a turn at the end of a field,or in a working position shown in FIGS. 7 and 8, or in a loweredposition in which it rests on the ground as shown in FIGS. 9 and 10.

The suspension system 16 allows the cutter head 6 to move verticallyrelative to the arm 12. Vertical movement of the cutter head 6 can beaccommodated without adjusting any energy accumulators associated withthe carrier arm, regardless of the length of the arm. The suspensionsystem 16 thus operates independently of any sideshift mechanism foradjusting the length of the carrier arm 12, thereby simplifyingoperation of the machine.

The stability of the cutter unit when it is in the raised transportposition is increased by the provision of the actuator 52 and thecompression spring 54, which exert a self-righting force on the cutterunit 6 when it is in the raised position. The actuator 52 and thesprings 54 are connected to the carrier arm 12 at pivot point 53 b,which is located higher than the virtual axis of rotation of the cutterunit 6 when the carrier arm is in a raised position, and they thereforeact to increase the stability of the cutter unit.

Because the connecting rods 28, 30 are subjected in use only to linearforces (i.e. forces of compression or tension that act along the axes ofthe connecting rods) and do not experience any bending forces they canbe relatively light in weight. At the same time, the risk of damage tothe suspension system when the cutter unit collides with an obstructionon the ground is substantially reduced.

When the mowing machine is in the transport configuration shown in FIG.1, the suspension system 16 supports the entire weight of the cutterunit 6 but prevents movement of the cutter unit in the width directionof the cutter unit. The cutter unit 6 can however move under gravity toa stable position relative to the carrier arm 12, which corresponds tothe raised position shown in FIGS. 5, 6 and 12. This prevents unwantedmovement of the cutter unit 6 during transportation along a road.

Various modifications of the apparatus described above are of coursepossible. For example, the arrangement of the connecting rods 28, 30 maybe reversed, so that the upper connecting rods 28 diverge from the frameplane towards the mo-plane and the lower connecting rods 30 convergefrom the frame plane to the mo-plane.

The ball joints 32 may be replaced by any other joints that allowrotation about two orthogonal axes, including for example universaljoints (Cardan joints).

The hydraulic actuator 52 may be replaced by any other suitable actuatorincluding, for example, an electric linear motor or a motor drivenscrew. Alternatively, the actuator 52 may be omitted entirely and theweight of the cutter unit may then be supported by resilient supportelements, for example springs or other resilient components.Furthermore, one or more of the springs 54, 60 that form part of thesuspension system may be omitted or replaced by other resilient supportelements, for example gas struts.

FIGS. 15 and 16 depict a second mowing machine 102 according to anembodiment of the invention, which is attached to the rear of a tractor104 through a conventional three-point mounting system. It should beunderstood however that the invention is also applicable to other kindsof agricultural machine including rakes, tedders, seeding machines andsoil working machines, in which an operating unit is attached to therear of a tractor 104.

The mowing machine 102 includes an operating unit 106 comprising acutter unit and a carrier assembly 108 for the cutter unit. The carrierassembly 108 includes a mounting structure 110 that is attached to thetractor's three-point mounting system, a carrier arm 112 that isattached to the mounting structure 110 through a pivot mechanism 114,and a suspension system 116 through which the cutter unit 106 issuspended from the free end of the carrier arm 112.

The pivot mechanism 114 allows the carrier arm 112 to be pivoted about apivot axis X that extends substantially parallel to the workingdirection D of the cutter unit 106 and includes an actuator 118, forexample a hydraulic ram, that can be activated to adjust the rotationalposition of the arm 112 about the pivot axis X. In FIG. 15 the mowingmachine is shown in a transport configuration in which the carrier arm112 is lifted to an upright position so that the cutter unit 106 islocated behind the cab of the tractor 104, while in FIG. 16 the carrierarm 112 is shown in a lowered position in which the carrier arm 112 andthe cutter unit 106 are substantially parallel to the ground. When thecarrier arm 112 is in the lowered position the cutter unit 106 may beadjusted relative to the carrier arm between a working position and aheadland position (shown in FIG. 16) in which it is raised slightlyabove the working position.

The carrier arm 112 includes an inner section 120, an actuator (notshown) and an outer section 122 that can be extended telescopicallyrelative to the inner section 120 to adjust the lateral position of thecutter unit 106 relative to the tractor 104. The actuator may forexample be a hydraulic ram located within the carrier arm 112. Thetelescopic carrier arm 112 thus allows for sideshift movement of thecutter unit 106 relative to the tractor 104. This allows the operatingposition of the cutter unit 106 to be adjusted laterally relative to thecentreline of the tractor 104. This makes it possible to adjust theoperating position of the cutter unit 106 during a mowing operation, forexample to ensure that the edge of the cut strip of crop is alignedcorrectly with the edge of a strip cut previously. Adjustment of thelateral position of the cutter unit may be carried out automatically orsemi-automatically, for example using an operating method as describedin EP1321027B1.

The cutter unit 106 is largely conventional and includes a plurality ofcutter heads (not shown) attached to a support frame 124 and an optionalconditioning unit 125 for conditioning the crop cut by the cutter heads.The cutter unit 106 is driven via a drive shaft (not shown) from thepower take-off unit of the tractor 104.

The cutter unit 106 is suspended from the free end of the carrier arm112 by the suspension system 116, which is shown most clearly in FIG.27. Components of the suspension system 116 are also shown schematicallyin FIG. 17, together with the carrier arm 112 and the support frame 124of the cutter unit. The suspension system 116 includes two pairs ofconnecting rods, comprising a pair of upper connecting rods 128 and apair of lower connecting rods 130. The connecting rods 128, 130 allextend approximately in the working direction of the mowing machine andare attached via ball joints 132 to the cutter unit 106 and the carrierarm 112.

The rear end of each connecting rod 128,130 is attached via a sphericalball joint to a mounting structure 134 that extends upwards from thesupport frame 124 of the cutter unit 106 and is located approximatelycentrally with respect to the working width of the cutter unit. In thisembodiment the mounting structure includes two pairs of tall innerplates 136 that are connected to the upper connecting rods 128 and twopairs of shorter outer plates 138 that are connected to the lowerconnecting rods 130. As with the first embodiment shown in FIG. 4, theball joints 132 at the rear ends of the connecting rods 128,130 lie in afirst plane referred to herein as the mo-unit plane. The ball joints 132at the rear ends of the upper connecting rods 128 are positioned moreclosely together than the ball joints 132 at the rear ends of the lowerconnecting rods 130.

The forward end of each connecting rod 128, 130 is attached via a secondspherical ball joint 132 to a second mounting structure 142 provided atthe free end of the carrier arm 112. In this embodiment the secondmounting structure 42 includes two pairs of upper plates 144 provided onthe upper part of the carrier arm 112 and two pairs of lower plates 146provided on the lower part of the carrier arm 112. Each of theconnecting rods 128, 130 is connected to one of these plates via asecond ball joint 132. As with the first embodiment shown in FIG. 4, thesecond ball joints lie in a second plane referred to herein as the frameplane. The ball joints at the forward ends of the lower connecting rods130 are positioned more closely together than the ball joints at theforward ends of the upper connecting rods 128.

The upper connecting rods 128 lie in an upper plane and the lowerconnecting rods lie in a lower plane, and in this embodiment the upperplane is parallel to the lower plane. More generally, a line normal tothe upper plane and a line normal to the lower plane are eachsubstantially perpendicular to a width axis of the cutter unit. Thisarrangement allows the cutter unit 106 to move substantially verticallyrelative to the carrier arm 112 while maintaining the cutter unit in anupright position (i.e. without rotation of the cutter unit about ahorizontal axis). Alternatively, the upper and lower planes may benon-parallel, in which case vertical movement of the cutter unitrelative to the carrier arm will cause a degree of rotation of thecutter unit 106 about a horizontal axis, which may be permissible incertain applications.

As explained above, the ends of the upper connecting rods 128 are closertogether in the mo-plane than the frame plane, and the upper connectingrods 128 therefore converge from the frame plane towards mo-plane.Conversely, the ends of the lower connecting rods 130 are further apartin the mo-plane than the frame plane and the lower connecting rods 130therefore diverge from the frame plane to the mo-plane. The upper andlower connecting rods 128, 130 therefore act like reversed A-frames,which prevent horizontal movement of the cutter unit 116 relative to thecarrier arm 112.

Because the connecting rods 128, 130 are connected to the carrier arm112 and the mounting structure 134 of the cutter unit 106 via balljoints, the cutter unit 106 is able to rotate relative to the carrierarm about an axis of rotation R that extends approximately in theworking direction of the cutter unit. This allows the cutter unit tofollow the contours of the ground while working.

As with the first embodiment shown in FIG. 4, the actual axis ofrotation R extends between two points, one in the mo-plane and the otherin the frame plane, each point being located at the intersection oflines drawn between the attachment points of diagonally opposed balljoints 132. The axis of rotation R therefore lies in a vertical planethat is parallel to the working direction D of the cutter unit, but isinclined downwards in the working direction.

It should be understood that the connecting rod arrangement illustratedin FIG. 17 may be inverted, whereby the upper pair of connecting rods128 diverge from the frame plane to the mo-plane and the lower pair ofarms 130 converge from the frame plane to the mo-plane. This does notaffect operation of the suspension system 116.

The suspension system 116 also includes an actuator 152 for adjustingthe height of the cutter unit 106 relative to the carrier arm 112, whichis shown most clearly in FIG. 27. In this example, the actuator 152comprises a hydraulic ram that extends from a first pivot point 153 abetween the rear ends of the upper connecting rods 128 to a second pivotpoint 153 b between the forward ends of the lower connecting rods 130.In this embodiment the first pivot point 153 a and the ball joints 132at the rear ends of the upper connecting rods 128 are coaxial, theactuator 152 being connected to the cutter unit 106 at the same heightas the upper connecting rods 128. By supplying hydraulic fluid to theram 152 it can be extended thereby lifting the cutter unit 106 to theraised position shown in FIGS. 18, 19 and 25. Reducing the quantity ofhydraulic fluid supplied to the ram 152 allows the cutter unit to fallunder gravity to the working position shown in FIGS. 20, 21 and 24, andsubsequently to the lowered position shown in FIGS. 22, 23 and 26, forexample for cleaning or maintenance.

The suspension system therefore allows the height of the cutter unit 106relative to the carrier arm 112 to be adjusted and allows the cutterunit to rotate about an axis R that extends substantially in the workingdirection D, but does not allow the cutter unit 106 to move laterallyrelative to the carrier arm (i.e. in a direction that is parallel to thewidth of the cutter unit). The cutter unit 106 can therefore rotate toaccommodate undulations in the surface of the ground. The height of thecutter unit 106 relative to the carrier arm 112 can also be adjustedeither to adjust the height of cut of the cutter unit, or to allow thecutter unit to be positioned in a raised headland position as shown inFIGS. 18 and 19 that allows the tractor to perform a turn at the end ofa field, or in a working position as shown in FIGS. 20 and 21, or in alowered position in which it rests on the ground as shown in FIGS. 22and 23.

The suspension system 116 allows the cutter head 106 to move verticallyrelative to the arm 112. Vertical movement of the cutter head 106 can beaccommodated without adjusting any energy accumulators associated withthe carrier arm 112, regardless of the length of the arm. The suspensionsystem 116 thus operates independently of any sideshift mechanism foradjusting the length of the carrier arm 112, thereby simplifyingoperation of the machine.

The stability of the cutter unit when it is in the raised transportposition is increased by the provision of the actuator 152, which exerta self-righting force on the cutter unit 106 when it is in the raisedposition. The actuator 152 is connected to the carrier arm 112 at pivotpoint 153 b, which is located higher than the virtual axis of rotation Rof the cutter unit 106 when the carrier arm is in a raised position, andit therefore acts to increase the stability of the cutter unit.

Because the connecting rods 128, 130 are subjected in use only to linearforces (i.e. forces of compression or tension that act along the axes ofthe connecting rods) and do not experience any bending forces they canbe relatively light in weight. At the same time, the risk of damage tothe suspension system when the cutter unit collides with an obstructionon the ground is substantially reduced.

When the mowing machine is in the transport configuration shown in FIG.15, the suspension system 116 supports the entire weight of the cutterunit 106 but prevents movement of the cutter unit in the width directionof the cutter unit. The cutter unit 106 can however move under gravityto a stable position relative to the carrier arm 112, which correspondsto the raised position shown in FIGS. 18, 19 and 25. This preventsunwanted movement of the cutter unit 106 during transportation along aroad.

Various modifications of the apparatus described above are of coursepossible. For example, the arrangement of the connecting rods 128, 130may be reversed, so that the upper connecting rods 128 diverge from theframe plane towards the mo-plane and the lower connecting rods 130converge from the frame plane to the mo-plane.

The ball joints 132 may be replaced by any other joints that allowrotation about two orthogonal axes, including for example universaljoints (Cardan joints).

The hydraulic actuator 152 may be replaced by any other suitableactuator including, for example, an electric linear motor or a motordriven screw. Alternatively, the actuator 152 may be omitted entirelyand the weight of the cutter unit may then be supported by resilientsupport elements, for example springs or other resilient components.

The suspension system comprising the connecting rods and optionally themounting structures, springs and actuator may be supplied separately forretrofitting to an existing cutter unit. Similarly, the carrier assemblycomprising the carrier arm and the suspension system may be suppliedseparately for retrofitting to an existing cutter unit.

As previously indicated, the invention is not limited to mowing machinesbut is also applicable to other kinds of agricultural machine includingrakes, tedders, seeding machines and soil working machines in which anoperating unit is attached to the rear of a tractor 4.

1. An agricultural machine comprising: an operating unit; and a carrierassembly for the operating unit, the carrier assembly including: acarrier arm; and a suspension system by which the operating unit issuspended from the carrier arm, said suspension system comprising a pairof upper connecting rods and a pair of lower connecting rods, each ofsaid upper and lower pairs of connecting rods being attached via jointsto the operating unit and the carrier arm, wherein one of said upper andlower pairs of connecting rods diverge in a working direction of theoperating unit and the other of said upper and lower pairs of connectingrods converge in a working direction of the operating unit.
 2. Anagricultural machine according to claim 1, wherein the suspension systemincludes a support mechanism configured to support the weight of theoperating unit.
 3. An agricultural machine according to claim 2, whereinthe support mechanism includes an actuator configured to adjust theheight of the operating unit relative to the carrier arm.
 4. Anagricultural machine according to claim 3, wherein the actuator isconfigured to act between the operating unit and the carrier arm.
 5. Anagricultural machine according to claim 1, wherein the upper connectingrods lie in an upper plane and the lower connecting rods lie in a lowerplane.
 6. An agricultural machine according to claim 5, wherein a linenormal to the upper plane and a line normal to the lower plane aresubstantially perpendicular to a width axis of the operating unit.
 7. Anagricultural machine according to claim 5, wherein the upper plane issubstantially parallel to the lower plane.
 8. An agricultural machineaccording to claim 1, wherein the carrier assembly includes a mountingstructure configured for mounting the machine on a carrier vehicle and apivot mechanism configured to allow pivoting movement of the carrier armrelative to the mounting structure about a pivot axis that extendssubstantially parallel to the working direction of the agriculturalmachine.
 9. An agricultural machine according to claim 8, wherein thecarrier assembly includes a drive mechanism for driving pivotingmovement of the carrier arm.
 10. An agricultural machine according toclaim 8, wherein the pivot mechanism is configured to provide forpivoting movement of the carrier arm between an upright position and alowered position.
 11. An agricultural machine according to claim 1,wherein the carrier arm includes an inner arm section and an outer armsection that can be extended relative to the inner arm section to adjustthe length of the carrier arm.
 12. An agricultural machine according toclaim 11, including an actuator for adjusting the length of the carrierarm.
 13. An agricultural machine according to claim 1, wherein themachine is a mowing machine and the operating unit is a cutter unit. 14.An agricultural mowing machine according to claim 13, wherein the cutterunit includes a plurality of rotary cutter heads.
 15. A carrier assemblyfor carrying the operating unit of an agricultural machine, the carrierassembly comprising: a carrier arm; and a suspension system by which theoperating unit can be suspended from the carrier arm, said suspensionsystem including: a mounting structure for attaching the suspensionsystem to an operating unit; and a pair of upper connecting rods and apair of lower connecting rods, each of said upper and lower pairs ofconnecting rods being attached via joints to the mounting structure andthe carrier arm, wherein a first pair of said upper and lower connectingrods diverge in a working direction of the operating unit and a secondpair of said upper and lower connecting rods converge in a workingdirection of the operating unit.
 16. A carrier assembly according toclaim 15, wherein the agricultural machine is a mowing machine and theoperating unit is a cutter unit.